Micro-dialysis probe

ABSTRACT

A micro-dialysis probe extending longitudinally between a proximal probe opening and a distal probe tip and having a supply line and a drainage line for a drip-feed solution. A tube may be provided for supporting the drainage line. A dialysis section, wherein the flow channel for the drip-feed solution experiences an inversion, is formed generally between the supply line and the drainage line, in the vicinity of the distal probe tip. The supply line and the drainage line are arranged substantially side by side and together form the probe shaft of the micro-dialysis probe.

PRIORITY CLAIM

This application is a continuation of International Application No.PCT/CH00/00389, filed on Jul. 18, 2000, which claims priority to GermanApplication No.199 37 099 C2, filed on Aug. 6, 1999, both of which areherein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a micro-dialysis probe having a supplyline and a drainage line for a drip-feed solution and a dialysis sectionpositioned generally therebetween. More specifically, the presentinvention relates to a micro-dialysis probe wherein solution flowingfrom the supply line to the drainage line experiences an inversion inflow in the area of the dialysis section.

2. Description of the Related Art

Implanted hollow fibers, hollow fiber loops or dialysis probes are usedfor micro-dialysis in medicine and biological research. Conventionaldialysis probes possess a tube-shaped shaft in which dialysate isdrained and which comprises a closed cylindrical membrane (hollow fibersealed on one side) into whose interior a thin tube protrudes, forsupplying the drip-feed solution. Between the drip-feed solution flowingback and the ambient medium, dialysis at the hollow fiber membrane leadsto a concentration equalisation in the permeable substances. Probes withthe same principle design are also known, in which the dialysis fiber issurrounded by a non-buckling casing or framework which it partiallyprotrudes out from, said dialysis fiber being supported by said casingor framework. Such a dialysis probe is known, for example, from DE 33 42170 C2.

In the use of viscous drip-feed solutions or at high flow rates inparticular, it is evident that the flow through such dialysis probes isnot optimal. Lateral pressure upon the probe can move the inner tubeslightly out of its central position and the flow profiles via thehollow cylinder are changed. The flow can slow up or come to astandstill on the side where the gap between the outer and innercylinder is very narrow, while a fast-flowing preferential path forms onthe opposite side. Moreover, a dead space arises in the shaft in whichthe dialysate is drained, due to its construction, at the transfer pointinto the drainage tube. Both of these lead to a delay in the adjustingof the equilibrium.

To stabilise the position of the inner tube in the hollow fiber, DE 19714 087 A1 has proposed, for such probes, surrounding the capillary witha profile. Profiles with such a small diameter and a central bore,however, can only be produced at great cost.

SUMMARY OF THE INVENTION

The present invention relates to a dialysis probe having a supply lineand a drainage line for a drip-feed solution and a dialysis sectionarranged generally therebetween. The dialysis probe is configured suchthat solution flowing from the supply line to the drainage lineexperiences an inversion in flow in the area of the dialysis section.Thus, the dialysis probe of the present invention provides stable flowguidance and thus a fast adjustment of the equilibrium. Further, in thedialysis probe of the present invention, flow-impeding dead spaces inthe dialysis section and in the supply line and drainage line aresubstantially avoided.

The supply line and drainage line are arranged generally side by side inaccordance with the invention, not one inside the other as in the priorart. Thus, the supply line and the drainage line together form a probeand can thus, through their own structure or by providing protectivedevices formed thereover, be stably developed such that mechanicalinfluences do not impede the flow of the drip-feed solution. While inthe prior art, for example in accordance with DE 33 42 170 C2, pressureon the outer hollow cylinder (i.e., the drainage line) automaticallyaffects the supply line within it, outside pressure on the probe doesnot similarly affect the supply line and drainage line of the invention.

A further advantage of the dialysis probe in accordance with theinvention is that the supply line and drainage line can each simply runstraight in or out of the rear part of the dialysis probe, and flowredirection —in which dead spaces are formed—can be largely avoided.

In an embodiment of the micro-dialysis probe in accordance with theinvention, the first drainage line in the direction of the flow consistsof a dialysis hollow fiber penetrating into the supply line behind theinversion, the hollow fiber being fastened in the area of the sealed tipof the probe such that a linear course of flow is achieved after theinversion, while at its other end it is sealed into a second stablesection of the drainage line. In this way, the drip-feed solution flowsthrough the whole cross-section of the dialysis hollow fiber in onedirection, and the dialysate is introduced into the drainage linelinearly, without a change in direction. The flow direction is hereinverted, as is necessary to enable the liquid to be supplied anddrained from one side, before it enters the dialysis hollow fiber, suchthat the dialysis itself is not impeded by disturbances in the flow. Thepreviously mentioned stable section is preferably a tube which forms theouter part of the drainage line, i.e. its supporting component. In thisway, the part of the tube in the area of the tip of the probe which liesover the hollow fiber, where the dialysis hollow fiber penetrates intothe supply line, can form a supporting section to mechanicallystrengthen this part of the probe.

The hollow fiber is preferably formed to be replaceable, andcorrespondingly sealed in, the tube and in particular its supportingsection comprising recesses via which the hollow fiber is exposedoutwards, to be able to perform dialysis. In this way, the supply line,and the supporting section arranged on the opposite side of the hollowfiber parallel to said supply line, form an outer framework whichmechanically shields the hollow fiber from the surrounding matrix oftissues without preventing direct liquid contact between the hollowfiber and the surrounding medium. The supply line and the drainage linecan in principle be separate parts, connected firmly at the tip and theside facing away from it, when assembled. However, it is particularlyfavourable if the supply line and the drainage line, which comprise aflow connection in their tip, are integrated into a single piece, forexample via a fixing material.

In a further preferred embodiment of the micro-dialysis probe inaccordance with the invention, the flow channel for the drip-feedsolution consists of a hollow fiber with a supporting profile insertedinto it which separates the supply line and the drainage line from eachother, the supporting profile comprising overflow openings in the areaof flow inversion. Here too, therefore, the principle is again realisedthat each of the supply line and the drainage line form, together withthe hollow fiber, a part of the outer wall of the probe, but areseparated and supported in such a way that the flow is not impeded. Inthis way, both the supporting function and flow guidance are assumed bythe profile. The supporting profile is thus designed in accordance withthe invention such that the volume of the hollow fiber through which theflow may pass consists of a number of elongated hollow spaces. Thesehollow spaces enable the drip-feed agent to flow into the tip of theprobe and to be re-circulated to the other side, wherein the flow isinverted by the overflow openings. Here, too, the flow in and out canlargely be achieved in a straight course of flow.

An embodiment of the micro-dialysis probe as described above ispreferred developed such that the hollow fiber at the supply line endand drainage line end of the probe is sealed into a probe shaft whichaccommodates and continues the supply line and the drainage lineseparately. Such a probe shaft ensures a further increase in stabilityand enables the necessary connections to be provided.

The supporting profile can be developed with a star-shapedcross-section, for example as a three- or four-armed star. On the otherhand, however, it is also possible to form the profile as a flatpartition which exhibits a rectangular or lenticular cross-section andis provided on one or both of its flat sides with fine bristles or knobswhich keep the hollow fiber wall at a distance.

The greatest mechanical stability, however, is achieved using a starprofile. In the case of a four-armed star profile, the drip-feedsolution is guided in two parallel channels as the supply line, whilethe other two channels form the drainage line. If a three-armed starprofile is used, the stretching of the hollow fiber material caused byswelling can be compensated for, if the dry hollow fiber is moved tautover the profile and appears in cross-section like a triangle withrounded corners. When the hollow fiber membrane is stretched, this againforms a circle in cross-section. In this three-armed embodiment of theprofile, a single supply line is accordingly provided, but two drainagelines. Since the hollow fiber is sufficiently supported from within, itcan be exposed to the matrix of tissues along its entire length.Dialysis then takes place both in the supply line as well as in thedrainage lines.

Although a higher flow rate prevails in the individual supply line dueto the smaller cross-section, an efficient exchange of material takealso take place here, since the concentration gradient between thedrip-feed solution and the surroundings is still at its greatest in thisarea. After the drip-feed solution has overflowed into the two paralleldrainage lines in the immediate vicinity of the tip, the flow rate ishalved, which promotes concentration equalisation between the substancespassing through the hollow fiber, since more time is available for thispurpose.

The supply line and/or drainage line of a micro-dialysis probe inaccordance with the invention should preferably have a substantiallylinear course, to largely rule out the formation of dead spaces in theflow.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail by way of twopreferred embodiments. There is shown:

FIG. 1 illustrates a perspective view of a longitudinal section of amicro-dialysis probe in accordance with a first embodiment of thepresent invention.

FIG. 2 illustrates a cross-sectional view of the embodiment of FIG. 1,taken along A—A of FIG. 1.

FIG. 3 illustrates a cross-sectional view of the embodiment of FIG. 1,taken along B—B of FIG. 1.

FIG. 4 illustrates a perspective view of a longitudinal section of amicro-dialysis probe in accordance with a second embodiment of thepresent invention.

FIG. 5 illustrates a cross-sectional view of the embodiment of FIG. 4,taken along C—C of FIG. 4.

FIG. 6 illustrates a cross-sectional view of the embodiment of FIG. 4,taken along D—D of FIG. 4.

FIG. 7 illustrates a cross-sectional view of the embodiment of FIG. 4,taken along E—E of FIG. 4.

FIG. 8 illustrates a cross-sectional view of the embodiment of FIG. 4,taken along F—F of FIG. 4.

DETAILED DESCRIPTION

FIG. 1 illustrates a micro-dialysis probe in accordance with a firstembodiment of the present invention. The micro-dialysis probe extendslongitudinally between a proximal probe opening and a distal probe tip.A supply line 1, or a supply channel, is provided through which thedrip-feed solution is introduced into the probe. A drainage line 6,formed by a hollow fiber 4, is provided for draining the drip-feedsolution from the probe. A tube 11 may be provided surrounding thedrainage line 6 for supporting the drainage line 6. The hollow fiber 4is may be formed to be replaceable, and correspondingly sealed in, thetube 11. The supply line 1 and drainage line 6 are arrangedsubstantially side-by-side and together form the probe shaft of themicro-dialysis probe. At the distal probe tip, the probe is sealed andpointed with a sealing material 13, to enable it to be introduced intosubcutaneous tissue. In the vicinity of the probe tip, a dialysisopening 10 is provided in the supply line 10. The hollow fiber 4penetrates from above into the dialysis opening 10 of the supply line 1.Flow connection between the supply line 1 and the hollow fiber 4 is thusformed with the aid of the shaping of the sealing material, such thatthe flow can be inverted without being substantially impeded. The hollowfiber 4 in the area of the opening 10 is sealed with the sealingmaterial such that there is no leakage. Thus, the drip-feed solutionflows through the whole cross-section of the dialysis hollow fiber inone direction and is introduced in the drainage line linearly without achange in direction. The flow direction is here inverted to enable theliquid to be supplied and drained from one side, before it enters thedialysis hollow fiber, such that the dialysis itself is not impeded bydisturbances in the flow.

In the area of the flow inversion, a dialysis section is formed. To formthe dialysis section, the tube 11 surrounding the drainage line 6 isprovided with recesses 5 in the area of the cross-sectional view of FIG.2, such that the hollow fiber 4 is here exposed to the surroundingtissue and dialysis can take place. The supply line 1, and thesupporting section of the tube 11 arranged on the opposite side of thehollow fiber 4 parallel to the supply line 1, form an outer frameworkwhich mechanically shields the hollow fiber 4 from the surroundingmatrix of tissues without preventing direct liquid contact between thehollow fiber 4 and the surrounding medium. The supply line 1 and thedrainage line 6 may be formed as separate parts, connected firmly at thedistal probe tip and the proximal probe opening. However, in a preferredembodiment, the supply line 1 and the drainage line 6, having a flowconnection, or dialysis section, near their tip, are integrated in asingle piece.

Only one supporting section 3 of the tube 11 lies over the hollow fiber4 in this area, to shield said fiber on this side from mechanicalpressure from without.

In its further course towards the proximal probe opening, opposite theprobe tip, the hollow fiber 4 is again surrounded by the tube 11, asshown in the cross-sectional view of FIG. 3. In this area, the hollowfiber is sealed by a carrier material (shown in grey) in the tube 11.The supply line 1 and the drainage line 6 with the surrounding tube 11are fixed to one another in this area using the fixing material 9, shownin FIG. 3. The dialysis probe thus forms an integral unit.

When considering this embodiment of the micro-dialysis probe inaccordance with the invention, as it is shown in FIG. 1, it then becomesclear on the one hand that no dead spaces, which could impede the flowand delay adjustment of the equilibrium, are created in the course ofthe flow, in particular during the supply and drainage of the drip-feedsolution. On the other hand, it is clearly shown that arranging thesupply line 1 and the drainage line 6 side by side allows a very stableprobe to be formed, in which even external mechanical effects can hardlyinterrupt the continuity of the flow. In short, both the supply line andthe drainage line can also be mechanically well protected, since theseparts are at least mostly arranged parallel on the outer wall of theprobe. In supply lines accommodated in the drainage line, as previouslyprovided by the prior art, this is not possible or only at very greatcost.

FIG. 4 illustrates a micro-dialysis probe of the present invention inaccordance with a second embodiment. The flow channel for the drip-feedsolution consists of a hollow fiber 8 with a supporting profile 2inserted into it which separates the supply line 1 and the drainage line6 from one another, the supporting profile 2 having at least one opening7 in the area of flow inversion. The supply line 1 and drainage line 6,together with the hollow fiber 8, form a part of the outer wall of theprobe, but are separated and supported such that the flow is notimpeded. The supporting function and flow guidance are assumed by theprofile 2. The supporting profile 2 is thus configured such that thevolume of the hollow fiber 8 through which the flow may pass consists ofa number of elongated hollow spaces. These hollow spaces enable thedrip-feed solution to flow into the probe tip and to be re-circulated tothe other side, wherein the flow is inverted by the overflow openings.

As shown in FIG. 4, the supply line channel 1 and drainage line channel6 lie, at the proximal end of the probe, opposite the probe tip, in aprobe shaft 12, where inserted hoses 14 and 15 are arranged. The probeshaft 12 accommodates and continues the supply line 1 and the drainageline 6 separately. The probe shaft 12 increases stability of themicro-dialysis probe. A profile 2 is attached to the left front face ofthe shaft 12, over which the hollow fiber 8 is pulled and sealed at thepoint of attachment. As shown, the profile has a three-armed star shape.The profile may alternately be shaped as a four-armed star or may beflat. If the profile is flat, it may exhibit a rectangular or lenticularcross-section and be provided on one or both of its flat sides with finebristles or knobs to support the hollow fiber and maintain it at adistance. The supply line 1 and the drainage line 6 are formed in thearea of the shaft 12 by the shaft itself, as shown in thecross-sectional view of FIG. 5. FIG. 6 is a cross-sectional view showinga lower supply line 1 and two upper drainage lines 6 being formed by theprofile 2 covered by the hollow fiber 8. The supply line 1 and thedrainage line 6 are separated from one another and extend generally inparallel. At the point of the micro-dialysis proe shown in FIG. 7, thecenter of the profile 2 is left open, such that an overflow opening 7 iscreated through which the drip-feed liquid can flow from the supply line1 into the drainage lines 6, thereby creating a primary dialysissection. Thus, in this embodiment, flow inversion takes place here. Ofcourse the overflow opening can be formed at a different point in themicro-dialysis probe and need not correspond exactly with thecross-sectional point of FIG. 7. The profile is sealed together with thehollow fiber at the tip by a sealing material 13, as can be seen in FIG.8. After passing the overflow opening 7, the drip-feed liquid flows intothe two drainage lines 6, which re-unite in the area of the shaft. Asshown, supply line and the drainage lines run side by side and aresupported from within by the profile 2, such that impedance of the flowthrough external influences is substantially prevented. In theembodiment shown, the flow is substantially linear and is guided in agenerally straight line, such that dead spaces and the impedance of theflow and delays in adjusting the equilibrium associated therewith aresubstantially avoided.

As discussed above, the profile may be formed in any suitable shape, forexample as a three or four-armed star or as flat with a rectangular orlenticular cross-section. A star-shaped profile is preferred as itachieves high mechanical stability. Using a four-armed star profile, thedrip-feed solution is guided in two parallel channels as the supplyline, and two parallel channels as the drainage line. Using athree-armed star profile, the stretching of the hollow fiber materialcaused by swelling may be compensated for, if the dry hollow fiber ismoved taut over the profile and appears in cross-section as a trianglewith rounded corners. When the hollow fiber membrane is stretched, acircle cross-section is again formed. In the three-armed star embodimentof the profile, a single supply line and two drainage lines areprovided. As the hollow fiber is supported from within, it may beexposed to the matrix of tissues along its entire length. Dialysis thentakes place both in the supply line as well as in the drainage lines.

Dialysis takes place along the entire section of the hollow fiber 8,from the shaft 12 up to the sealing material 13, both in the supply line1 and in the drainage lines 6. Because of the smaller cross-section, thesolution admittedly flows faster in the supply line 1, however thehighest concentration gradient is also present in this area, such thatsufficient dialysis takes place. This concentration gradient isadmittedly lower in the two drainage line sections, however the contactarea here is even greater and the flow rate is only a half, such that aneffective concentration equalisation can also be achieved in this area.Components 14 and 15 can be developed as supply and drainage hosesrespectively, and simply sealed into the shaft at their insertionpoints, such that the solution is prevented from escaping.

In the foregoing description preferred embodiments of the invention havebeen presented for the purpose of illustration and description. They arenot intended to be exhaustive or to limit the invention to the preciseform disclosed. Obvious modifications or variations are possible inlight of the above teachings. The embodiments were chosen and describedto provide the best illustration of the principals of the invention andits practical application, and to enable one of ordinary skill in theart to utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth they are fairly, legally, and equitably entitled.

1. A micro-dialysis probe comprising: a proximal probe opening providing access to a supply line and a drainage line; a distal probe tip for introducing the probe into subcutaneous tissue; a supply line for introducing drip-feed solution into the probe, the supply line having a dialysis opening in the vicinity of the probe tip; a drainage line formed as a hollow fiber, the hollow fiber being exposed to surrounding tissue in the vicinity of the probe tip; a dialysis section being formed between the supply line and the drainage line in the area of the supply line dialysis opening and the exposure of the hollow fiber to surrounding tissue; the drip-feed solution flowing through the supply line experiencing an inversion in the area of the dialysis section and between the supply line and the drainage line, the supply line and drainage line together forming a probe shaft, the supply line and the drainage line being arranged as separate hollow channels of the probe shaft.
 2. The micro-dialysis probe of claim 1, wherein the probe tip is pointed and sealed with a sealing material.
 3. The micro-dialysis probe of claim 1, wherein the supply line and the drainage line are fixed to one another using a fixing material in the area of the probe shaft between the proximal probe opening and the dialysis section.
 4. The micro-dialysis probe of claim 1, further including a tube surrounding the drainage line, the tube having recesses to expose the hollow fiber to surrounding tissue in the vicinity of the probe tip.
 5. The micro-dialysis probe of claim 4, wherein the supply line and the drainage line, together with the tube surrounding the drainage line, are fixed to one another using a fixing material in the area of the probe shaft between the proximal probe opening and the dialysis section.
 6. The micro-dialysis probe of claim 1, wherein the supply line and the drainage line each extend substantially linearly.
 7. The micro-dialysis probe of claim 1, wherein the supply line and the drainage line are arranged substantially side-by-side.
 8. The micro-dialysis probe of claim 1, wherein the hollow fiber of the drainage line penetrates into the supply line proximally of the inversion, the hollow fiber being fixed in the area of the probe tip such that a linear course of flow is achieved distal of the inversion, while proximally of the inversion the hollow fiber is sealed in a tube surrounding the drainage line.
 9. The micro-dialysis probe of claim 8, wherein a section of the tube lies over the hollow fiber in the area of the probe tip and thereby forms a supporting section for the hollow fiber.
 10. The micro-dialysis probe of claim 9, wherein the supply line and supporting section together form an outer framework that shields the hollow fiber from surrounding tissues.
 11. The micro-dialysis probe of claim 1, wherein the hollow fiber is formed to be replaceable and is sealed in the tube.
 12. The micro-dialysis probe of claim 1, wherein the shaft formed by the supply line and the drainage line further includes a supporting profile for separating the supply line and the drainage line from each other, the supporting profile including overflow openings in the area of flow inversion.
 13. The micro-dialysis probe of claim 12, wherein the profile is star-shaped.
 14. The micro-dialysis probe of claim 13, wherein the profile is star-shaped as a three-armed star.
 15. The micro-dialysis probe of claim 13, wherein the profile is star-shaped as a four-armed star.
 16. The micro-dialysis probe of claim 12, wherein the profile is flat.
 17. The micro-dialysis probe of claim 16, wherein the profile comprises bristles or knobs on at least one of its flat sides to support the hollow fiber.
 18. The micro-dialysis probe of claim 17, wherein the supply line and the drainage line each extend substantially linearly.
 19. A micro-dialysis probe comprising: a probe shaft having a proximal end and a distal probe tip; a hollow fiber forming a supply line for introducing drip-feed solution into the probe and a drainage line, the supply line and drainage line being arranged as separate hollow channels of the probe shaft and together being formed by the shaft itself, the supply line and the drainage line extending substantially side-by-side; a supporting profile inserted into the hollow fiber, the supporting profile separating the supply line from the drainage line, the supporting profile at least one overflow opening, the drip-feed liquid flowing from the supply line into the drainage line in the area of the overflow opening, the drip-feed liquid there experiencing an inversion.
 20. The micro-dialysis probe of claim 19, further comprising a primary dialysis section in the area of flow inversion between the supply line and the drainage line.
 21. The micro-dialysis probe of claim 19, further comprising a dialysis section extending from the shaft to the probe tip and within both the supply line and the drainage line.
 22. The micro-dialysis probe of claim 19, wherein the supply line and the drainage extend substantially linearly.
 23. The micro-dialysis probe of claim 19, wherein the supply line and the drainage line are arranged substantially side-by-side.
 24. The micro-dialysis probe of claim 19, wherein the drainage line comprises two drainage channels.
 25. The micro-dialysis probe of claim 19, wherein the supply line is accommodated by a supply hose inserted in the probe shaft.
 26. The micro-dialysis probe of claim 19, wherein the drainage line is accommodated by a drainage hose inserted in the probe shaft.
 27. The micro-dialysis probe of claim 19, wherein the supply line and drainage line are integrated by a fixing material.
 28. The micro-dialysis probe of claim 19, further including a supporting profile for separating the supply line and the drainage line from each other, the supporting profile including overflow openings in the area of flow inversion.
 29. The micro-dialysis probe of claim 28, wherein the profile is star-shaped.
 30. The micro-dialysis probe of claim 29, wherein the profile is star-shaped as a three-armed star.
 31. The micro-dialysis probe of claim 29, wherein the profile is star-shaped as a four-armed star.
 32. The micro-dialysis probe of claim 28, wherein the profile is flat.
 33. The micro-dialysis probe of claim 32, wherein the profile comprises bristles or knobs on at least one flat side to support the hollow fiber.
 34. A micro-dialysis probe comprising: a proximal probe opening providing access to a supply line and a drainage line; a distal probe tip for introducing the probe into subcutaneous tissue; a supply line for introducing drip-feed solution into the probe, a drainage line; a dialysis section being formed between the supply line and the drainage line; the drip-feed solution flowing through the supply line in a flow direction, the flow direction being reversed in the area of the dialysis section and between the supply line and the drainage line.
 35. The micro-dialysis probe of claim 34, wherein the drainage line is formed as a hollow fiber, the hollow fiber being exposed to surrounding tissue in the area of the dialysis section.
 36. The micro-dialysis probe of claim 35, further including a tube surrounding the drainage line, the tube having recesses to expose the hollow fiber to surrounding tissue in the area of the dialysis section.
 37. The micro-dialysis probe of claim 36, wherein the hollow fiber is formed to be replaceable and is sealed in the tube.
 38. The micro-dialysis probe of claim 34, wherein the supply line and the drainage line each extend substantially linearly.
 39. The micro-dialysis probe of claim 34, wherein the supply line and the drainage line are arranged substantially side-by-side.
 40. The micro-dialysis probe of claim 34, wherein the supply line and the drainage line are formed by a hollow fiber.
 41. The micro-dialysis probe of claim 40, wherein the supply line and the drainage line extend substantially side-by-side.
 42. The micro-dialysis probe of claim 40, wherein the supply line and the drainage line extend substantially linearly.
 43. The micro-dialysis probe of claim 40, further including a supporting profile for separating the supply line and the drainage line from each other, the supporting profile including overflow openings in the area in which the flow direction is reversed.
 44. The micro-dialysis probe of claim 40, wherein the profile is star-shaped.
 45. The micro-dialysis probe of claim 44, wherein the profile is star-shaped as a three-armed star.
 46. The micro-dialysis probe of claim 44, wherein the profile is star-shaped as a four-armed star.
 47. The micro-dialysis probe of claim 40, wherein the profile is flat.
 48. The micro-dialysis probe of claim 47, wherein the profile comprises bristles or knobs on at least one flat side to support the hollow fiber. 